Small NdFeB Magnets in Smartphones
Neodymium (NdFeB) magnets are an invisible part of every smart phone. These tiny magnets are critical to the function of the phone, working quietly behind the scenes inside the phone case. These internal magnets are typically used in the speaker, receiver, vibration mode motor, taptic feedback motor, and camera auto-focus mechanism.
External smart phone uses for NdFeB magnets include ear buds, earphones and wall chargers –the kind of wall chargers that use magnetic connectors. Since speaker designs use 3-5 magnets per speaker, the quantity of magnets-per-phone adds up quickly. Smart phones can have up to 14 small magnets inside.
Neodymium N48 and N52 Speaker Phone Magnets
The first speaker phone magnets were single-magnet designs. But smart phones have gotten thinner, and consumers demand higher-quality sound and reliability from their smart phones, so now the number of magnets in the speaker has increased to 2-5 magnets as designers create form factors that are compatible with these new requirements.
These magnets get glued into an assembly that is subjected to elevated temperatures during processing, so the engineers must select magnet grades that can withstand the heat of these processes. Since the magnets are so small, designers use N48 and N52 magnets – two of the strongest available grades- because performance-per-unit volume is critical in such tight spaces. These strong magnets are also supplied in high-temperature grades due to the temperatures they see during the bonding process.
The receiver is the telephone microphone. Like speaker phones, receivers were originally made with a single magnet, but they are now typically a two-magnet design, and as with speaker magnets, the two-magnet design is due to the thinner design of the latest high-tech smart phones.
Receivers made with high-energy-product Neodymium magnets have a greater dynamic range, delivering a high-fidelity reproduction of sound to the downstream digital processing equipment.
Autofocus Motor for Smart Phone Camera
It might be surprising to note that the autofocus motor is actually a voice coil motor. A voice coil motor is what drives an audio speaker, but Voice Coil Motors are used in other applications where precision is important.
Autofocus cameras typically use voice coil motors (VCMs) because VCMs are very quick and precise over a short distance, and they are designed to move a speaker dome in the same manner that camera lenses move. Autofocus motors use 2-4 magnets per camera.
Neodymium magnets are used for voice coil motors in smart phones because even a very small magnet is very powerful and can actuate the auto-focus mechanism in a fraction of a second. The high strength of NdFeB magnets has been a major factor in driving improvements in smart phone camera technology and has led to better and cheaper cameras.
Vibration Motors and Taptic Feedback Motors
The vibration motor has been around a long time. It’s the silent ring motor for when you set your phone to vibrate. Vibration motors use one magnet.
Earbuds, Earphones and Headsets
Have you noticed how much better earphones and headsets have gotten in the last few years? NdFeB magnets have a lot to do with that. Each earphone/earbud or headset uses 2-4 magnets. That’s 1-2 magnets per side.
Neodymium magnets have made earphones smaller, and the sound quality has greatly improved compared to older earphones made with older technology. High-quality earbuds would not exist without the miniaturization made possible by high-tech NdFeB magnets.
Earbud magnets are so small that the volume of material is small. That’s true, but we make millions of these tiny magnets every year, so the total volume of these tiny magnets is substantial.